I'm a doctor. I've been trained to select, evaluate and prescribe medicines. I have an FP10 prescription pad which I carry around with me so I can provide medication to people I see where so ever I chance upon them.
It may seem curious, then, that the most frequent change I make to medication regimens is to stop a medicine rather than to start one.
Often folk have been prescribed a medicine that usually was wholly appropriate at that point, in the past, when it was initiated. Then when I see them the drug's causing side effects or it's working in unhelpful ways.
It's done it's job but it's now run it's course and can be stopped.
A common example would be antidepressants. Someone has something bad happen (like being told they have cancer) and their mood, naturally, drops. It stays low. An antidepressants is started to help them cope (and sometimes it's indicated, other times the person isn't depressed they're simply very sad 'cause life's awful). In any case, the medicine's used and time passes. When they're still feeling low and referred to me they're often at a stage where they're accepting that life's not peachy and they're coping well enough, but feel appropriately sad. Being sad because life's awful is a normal human emotion, it's not an illness and isn't depression. Antidepressants like fluoxetine are often started to "pep people up" with a bit of vim and vigour but the alerting qualities can make people restless. Having energy, but not purposeful, directed energy, makes people feel ill at ease and unable to relax. Stopping the antidepressant and giving explanation and support is usually more helpful than prescribing more.
Often folks may be on medicine for other problems that start to affect their mental well being. If physically frail and losing health, losing energy, losing mobility so losing independence mood can, understandably, drop. Some medicines, like atenolol for blood pressure/heart problems, can not uncommonly lower mood. Opiate analgesics can cause mood disturbance. Often, stopping these medicines (and swapping to another if still needed) can help moods strikingly, along with other support.
I'm struck of late by how prescribing really isn't necessary for many folk much of the time.